Caption: Optical fibre, animation. The cutaway view first shows a beam of light bouncing down the inside of the fibre, which happens in short-range multi-mode fibres. The core diameter then narrows to show light as it travels down a single-mode fibre. Single-mode fibres carry information long distances, including between continents. Charles K Kao was awarded the 2009 Nobel Prize for Physics for his work on single-mode fibres.